Not much others haven't said, but adding medipacks to save survivors from death or something would be nice.
Explosives are pretty much useless. Buying the building and buying the explosives is too much, especially for their poor range and damage.
I think you're supposed to hold the buttons when running and jumping. Especially when running. The tip of the cart should be around the 2 o clock position. Then let the cart fall naturally. Don't balance it near the end. Then hope the momentum gets to 600.
Got past 600 several times like that and don't ever want to play this ever again.